Tailored spectroscopic and optical properties in rare earth-activated glass-ceramics planar waveguides

Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing to develop interesting new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. At the state of art the fabrication techniques based on bottom-up and top-down approaches appear to be viable although a specific effort is required to achieve the necessary reliability and reproducibility of the preparation protocols. In particular, the dependence of the final product on the specific parent glass and on the employed synthesis still remain an important task of the research in material science. Glass-ceramic waveguides overcome some of the efficiency problems experienced with conventional waveguides. These two-phase materials are composed of nanocrystals embedded in an amorphous matrix. The respective volume fractions of the crystalline and amorphous phases determine the properties of the glass ceramic. They also represent a valid alternative to widely used glass hosts such as silica as an effective optical medium for light propagation and luminescence enhancement. Looking to application, the enhanced spectroscopic properties typical of glass ceramic in respect to those of the amorphous structures constitute an important point for the development of integrated optics devices, including optical amplifiers, monolithic waveguide laser, novel sensors, coating of spherical microresonators, and up and down converters for solar energy exploitation. This lecture presents an overview of the state of art in glass ceramics focusing the discussion on photonics application, and evidences the capital scientific and technological interest of this kind of two-phase materials. We will discussdifferent kind of oxide- and fluoride-based glass-ceramic waveguides activated by rare earth ions and their viability for different photonic applications.